Pakistan's military says the United States has vacated a base following a deadline given by Islamabad in protest at U.S. air strikes two weeks ago.

The Shamsi air base in the southwestern province of Baluchistan was believed to have been used in CIA drone attacks against Taliban and Al-Qaeda targets in Pakistan's tribal areas bordering Afghanistan.

Prime Minister Yusuf Raza Gilani

Following the November air strikes which killed 24 Pakistani troops on the Afghan border, Islamabad also blocked American and NATO convoys into Afghanistan via Pakistan.

Pakistani Prime Minister Yusuf Raza Gilani said the blocking may continue for several weeks.

Asked by the BBC if he still believed the attacks had been deliberate and pre-planned, Gilani replied: "Apparently so."

NATO has apologized for the air strikes, while the United States described the deaths as a tragedy.